"Freedom Road" may be the strongest soporific you can get without a prescription. It's a video Quaalude. And Muhammad Ali's TV-movie acting debut proves an entirely unnecessary career diversion for the Hercules of self-publicists in the four-hour NBC movie to be shown in two parts, tonight and tomorrow night at 9 on Channel 4.

Apparently someone's cockamamie notion of conscientious historical drama, "Freedom Road," from a 1944 novel by Howard Fast, tries to passs inert self-righteousness off as narrative energy. As written by David Zelag Goodman and directed by the late Jan Kadar, it's the kind of "quality" stuff that sends you ransacking the airwaves for a rejuvenating jolt of spirited mindless escapism.

Calling Sheriff Lobo! Calling Sheriff Lobo!

Fast is one of those unfortunate Hollywood lefties punished for his naivete with the overkill of the blacklist. Of course today that is such a badge of honor that his work is being systematically overvalued. Still, "Freedom Road" could never have been as minor a novel as it is a television show.

Ali, as the fictional ex-slave Gideon Jackson -- a supposedly galvanizing ultra-achiever -- is a major liability, with his thoughtlessly mumbled line readings and repertory of vacant stares. But he shouldn't get all the blame. The whole production suffers from a slapdash torpor that makes it a milestone in the animals of enervation.

As a foil for Jackson -- determined to lead South Carolina's blacks and poor whites constructively through Reconstruction -- Kris Kristofferson plays, in a manner more desultory even than usual, a snarling racist who nevertheless enlists in Jackson's effort in the name of survival. Progress is repeatedly interrupted by the Ku Klux Klan, who raid the heroes and the movie at too-regular intervals.

Kristofferson proves as negligible a presence as Ali, and rumors of backstage tiffs between them are not hard to swallow since they are often photographed as if each is on a different continent. Ali apparently felt that his mere participation was effort enough; if no one could get up the nerve to suggest refinements in his acting technique at least they could have told him to speak up.

Half the time he talks so quietly that June Allyson could drown him out whispering.

The dreadful underacting is complemented with such fits of dreadful overacting as Edward Herrmann as chief racist a devious businessman done up to look like Snidely Whiplash but written with less depth of character. The only excuses for interesting characters are a blind girl and an old man who occasionally drop by to comment on the action. At least the pathos they contribute is proficient, unlike almost everything else about the film.

Director Kadar is best known for "The Shop on Main Street," Oscar-winner as Best Foreign Film in 1965. He was, one presumes, not responsible for the offbeat editing of such sequences as track-laying for a new railroad, but nothing in the film can be said to end his career on a note of triumph.

Even for a TV movie "Freedom Road" is so badly shot and its scenes so poorly paced that it looks as if it were made the week after the motion picture camera was invented.